/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with this
 * work for additional information regarding copyright ownership. The ASF
 * licenses this file to You under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package org.apache.commons.exec;

import org.apache.commons.exec.util.StringUtils;

import java.io.File;
import java.util.HashMap;
import java.util.Iterator;
import java.util.StringTokenizer;
import java.util.Vector;
import java.util.Map;

/**
 * CommandLine objects help handling command lines specifying processes to
 * execute. The class can be used to a command line by an application.
 */
public class CommandLine {

	/**
	 * The arguments of the command.
	 */
	private final Vector arguments = new Vector();

	/**
	 * The program to execute.
	 */
	private final String executable;

	/**
	 * A map of name value pairs used to expand command line arguments
	 */
	private Map substitutionMap;

	/**
	 * Was a file being used to set the executable?
	 */
	private final boolean isFile;

	/**
	 * Create a command line from a string.
	 * 
	 * @param line
	 *            the first element becomes the executable, the rest the
	 *            arguments
	 * @return the parsed command line
	 * @throws IllegalArgumentException
	 *             If line is null or all whitespace
	 */
	public static CommandLine parse(final String line) {
		return parse(line, null);
	}

	/**
	 * Create a command line from a string.
	 * 
	 * @param line
	 *            the first element becomes the executable, the rest the
	 *            arguments
	 * @param substitutionMap
	 *            the name/value pairs used for substitution
	 * @return the parsed command line
	 * @throws IllegalArgumentException
	 *             If line is null or all whitespace
	 */
	public static CommandLine parse(final String line, Map substitutionMap) {

		if (line == null) {
			throw new IllegalArgumentException("Command line can not be null");
		} else if (line.trim().length() == 0) {
			throw new IllegalArgumentException("Command line can not be empty");
		} else {
			String[] tmp = translateCommandline(line);

			CommandLine cl = new CommandLine(tmp[0]);
			cl.setSubstitutionMap(substitutionMap);
			for (int i = 1; i < tmp.length; i++) {
				cl.addArgument(tmp[i]);
			}

			return cl;
		}
	}

	/**
	 * Create a command line without any arguments.
	 * 
	 * @param executable
	 *            the executable
	 */
	public CommandLine(String executable) {
		this.isFile = false;
		this.executable = getExecutable(executable);
	}

	/**
	 * Create a command line without any arguments.
	 * 
	 * @param executable
	 *            the executable file
	 */
	public CommandLine(File executable) {
		this.isFile = true;
		this.executable = getExecutable(executable.getAbsolutePath());
	}

	/**
	 * Copy constructor.
	 * 
	 * @param other
	 *            the instance to copy
	 */
	public CommandLine(CommandLine other) {
		this.executable = other.getExecutable();
		this.isFile = other.isFile();
		this.arguments.addAll(other.arguments);

		if (other.getSubstitutionMap() != null) {
			this.substitutionMap = new HashMap();
			Iterator iterator = other.substitutionMap.keySet().iterator();
			while (iterator.hasNext()) {
				Object key = iterator.next();
				this.substitutionMap.put(key,
						other.getSubstitutionMap().get(key));
			}
		}
	}

	/**
	 * Returns the executable.
	 * 
	 * @return The executable
	 */
	public String getExecutable() {
		// Expand the executable and replace '/' and '\\' with the platform
		// specific file separator char. This is safe here since we know
		// that this is a platform specific command.
		return StringUtils.fixFileSeparatorChar(expandArgument(executable));
	}

	/**
	 * Was a file being used to set the executable?
	 * 
	 * @return true if a file was used for setting the executable
	 */
	public boolean isFile() {
		return isFile;
	}

	/**
	 * Add multiple arguments. Handles parsing of quotes and whitespace.
	 * 
	 * @param arguments
	 *            An array of arguments
	 * @return The command line itself
	 */
	public CommandLine addArguments(final String[] arguments) {
		return this.addArguments(arguments, true);
	}

	/**
	 * Add multiple arguments.
	 * 
	 * @param arguments
	 *            An array of arguments
	 * @param handleQuoting
	 *            Add the argument with/without handling quoting
	 * @return The command line itself
	 */
	public CommandLine addArguments(final String[] arguments,
			boolean handleQuoting) {
		if (arguments != null) {
			for (int i = 0; i < arguments.length; i++) {
				addArgument(arguments[i], handleQuoting);
			}
		}

		return this;
	}

	/**
	 * Add multiple arguments. Handles parsing of quotes and whitespace. Please
	 * note that the parsing can have undesired side-effects therefore it is
	 * recommended to build the command line incrementally.
	 * 
	 * @param arguments
	 *            An string containing multiple arguments.
	 * @return The command line itself
	 */
	public CommandLine addArguments(final String arguments) {
		return this.addArguments(arguments, true);
	}

	/**
	 * Add multiple arguments. Handles parsing of quotes and whitespace. Please
	 * note that the parsing can have undesired side-effects therefore it is
	 * recommended to build the command line incrementally.
	 * 
	 * @param arguments
	 *            An string containing multiple arguments.
	 * @param handleQuoting
	 *            Add the argument with/without handling quoting
	 * @return The command line itself
	 */
	public CommandLine addArguments(final String arguments,
			boolean handleQuoting) {
		if (arguments != null) {
			String[] argumentsArray = translateCommandline(arguments);
			addArguments(argumentsArray, handleQuoting);
		}

		return this;
	}

	/**
	 * Add a single argument. Handles quoting.
	 * 
	 * @param argument
	 *            The argument to add
	 * @return The command line itself
	 * @throws IllegalArgumentException
	 *             If argument contains both single and double quotes
	 */
	public CommandLine addArgument(final String argument) {
		return this.addArgument(argument, true);
	}

	/**
	 * Add a single argument.
	 * 
	 * @param argument
	 *            The argument to add
	 * @param handleQuoting
	 *            Add the argument with/without handling quoting
	 * @return The command line itself
	 */
	public CommandLine addArgument(final String argument, boolean handleQuoting) {

		if (argument == null) {
			return this;
		}

		// check if we can really quote the argument - if not throw an
		// IllegalArgumentException
		if (handleQuoting) {
			StringUtils.quoteArgument(argument);
		}

		arguments.add(new Argument(argument, handleQuoting));
		return this;
	}

	/**
	 * Returns the expanded and quoted command line arguments.
	 * 
	 * @return The quoted arguments
	 */
	public String[] getArguments() {

		Argument currArgument;
		String expandedArgument;
		String[] result = new String[arguments.size()];

		for (int i = 0; i < result.length; i++) {
			currArgument = (Argument) arguments.get(i);
			expandedArgument = expandArgument(currArgument.getValue());
			result[i] = (currArgument.isHandleQuoting() ? StringUtils
					.quoteArgument(expandedArgument) : expandedArgument);
		}

		return result;
	}

	/**
	 * @return the substitution map
	 */
	public Map getSubstitutionMap() {
		return substitutionMap;
	}

	/**
	 * Set the substitutionMap to expand variables in the command line.
	 * 
	 * @param substitutionMap
	 *            the map
	 */
	public void setSubstitutionMap(Map substitutionMap) {
		this.substitutionMap = substitutionMap;
	}

	/**
	 * Returns the command line as an array of strings.
	 * 
	 * @return The command line as an string array
	 */
	public String[] toStrings() {
		final String[] result = new String[arguments.size() + 1];
		result[0] = this.getExecutable();
		System.arraycopy(getArguments(), 0, result, 1, result.length - 1);
		return result;
	}

	/**
	 * Stringify operator returns the command line as a string. Parameters are
	 * correctly quoted when containing a space or left untouched if the are
	 * already quoted.
	 * 
	 * @return the command line as single string
	 */
	public String toString() {
		return StringUtils.toString(toStrings(), " ");
	}

	// --- Implementation ---------------------------------------------------

	/**
	 * Expand variables in a command line argument.
	 * 
	 * @param argument
	 *            the argument
	 * @return the expanded string
	 */
	private String expandArgument(final String argument) {
		StringBuffer stringBuffer = StringUtils.stringSubstitution(argument,
				this.getSubstitutionMap(), true);
		return stringBuffer.toString();
	}

	/**
	 * Crack a command line.
	 * 
	 * @param toProcess
	 *            the command line to process
	 * @return the command line broken into strings. An empty or null toProcess
	 *         parameter results in a zero sized array
	 */
	private static String[] translateCommandline(final String toProcess) {
		if (toProcess == null || toProcess.length() == 0) {
			// no command? no string
			return new String[0];
		}

		// parse with a simple finite state machine

		final int normal = 0;
		final int inQuote = 1;
		final int inDoubleQuote = 2;
		int state = normal;
		StringTokenizer tok = new StringTokenizer(toProcess, "\"\' ", true);
		Vector v = new Vector();
		StringBuffer current = new StringBuffer();
		boolean lastTokenHasBeenQuoted = false;

		while (tok.hasMoreTokens()) {
			String nextTok = tok.nextToken();
			switch (state) {
				case inQuote:
					if ("\'".equals(nextTok)) {
						lastTokenHasBeenQuoted = true;
						state = normal;
					} else {
						current.append(nextTok);
					}
					break;
				case inDoubleQuote:
					if ("\"".equals(nextTok)) {
						lastTokenHasBeenQuoted = true;
						state = normal;
					} else {
						current.append(nextTok);
					}
					break;
				default:
					if ("\'".equals(nextTok)) {
						state = inQuote;
					} else if ("\"".equals(nextTok)) {
						state = inDoubleQuote;
					} else if (" ".equals(nextTok)) {
						if (lastTokenHasBeenQuoted || current.length() != 0) {
							v.addElement(current.toString());
							current = new StringBuffer();
						}
					} else {
						current.append(nextTok);
					}
					lastTokenHasBeenQuoted = false;
					break;
			}
		}

		if (lastTokenHasBeenQuoted || current.length() != 0) {
			v.addElement(current.toString());
		}

		if (state == inQuote || state == inDoubleQuote) {
			throw new IllegalArgumentException("Unbalanced quotes in "
					+ toProcess);
		}

		String[] args = new String[v.size()];
		v.copyInto(args);
		return args;
	}

	/**
	 * Get the executable - the argument is trimmed and '/' and '\\' are
	 * replaced with the platform specific file separator char
	 * 
	 * @param executable
	 *            the executable
	 * @return the platform-specific executable string
	 */
	private String getExecutable(final String executable) {
		if (executable == null) {
			throw new IllegalArgumentException("Executable can not be null");
		} else if (executable.trim().length() == 0) {
			throw new IllegalArgumentException("Executable can not be empty");
		} else {
			return StringUtils.fixFileSeparatorChar(executable);
		}
	}

	/**
	 * Encapsulates a command line argument.
	 */
	class Argument {

		private final String value;
		private final boolean handleQuoting;

		private Argument(String value, boolean handleQuoting) {
			this.value = value.trim();
			this.handleQuoting = handleQuoting;
		}

		private String getValue() {
			return value;
		}

		private boolean isHandleQuoting() {
			return handleQuoting;
		}
	}
}
